Senate Democrats on Wednesday voted in a show of unity in the face of intense GOP opposition to cut off a bitter debate on their version of President Obama's health insurance overhaul, setting up a final passage vote on Christmas eve.

The Senate voted 60-39 to advance the legislation to the finish line with a final passage vote scheduled for 7 a.m. ET Thursday, the first Christmas eve vote since 1895, according to a Senate historian.

"Today is a victory -- a victory for families, a victory for small business owners...for the American economy for generations to come," Sen. Max Baucus, D-Mont., said at a news conference with other Senate Democrats.

Obama, in an interview with PBS Newshour, said he's "very satisfied" that the Senate is on the verge of passing the bill.

During a series of seven votes wrapping up the health care debate, Senate Republicans failed in their last-ditch efforts to derail the bill.

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The Senate voted 60-39 to reject Sen. John Ensign's call to examine the constitutionality of a health care mandate central to the overhaul bill.

The Nevada Republican wanted to determine whether it was constitutional for the federal government to require Americans to purchase health insurance.

The Senate also rejected a constitutional challenge from Texas Sen. Kay Bailey Hutchison, who argued that the bill would infringe state regulations of health insurance, and voted down South Carolina Sen. Jim DeMint's amendment to ban earmarks in the legislation.

Earlier Wednesday Republicans, emboldened by a new letter from the Congressional Budget Office, accused Democrats on Wednesday of "Bernie Madoff accounting" for double counting the savings from Medicare as a means to pay for the Senate health care bill.

Sen. Jeff Sessions, R-Ala, said the nearly $500 billion in cuts to Medicare actually will add $300 billion to the deficit -- a figure that contradicts the argument by Democrats that the bill will reduce the deficit by $132 billion over 10 years.

"The real score on this legislation is that it would cause the deficit to increase, and not be a surplus as the president has promised," Sessions told Fox News. "And a lot members of our Congress have said I won't vote for this bill unless it's deficit neutral. It's not deficit neutral. It will add to the debt. That's clear today."

A spokesman for Senate Majority Leader Harry Reid claimed the CBO letter dealt explicitly with Medicare, not the overall short and long term budgetary impact of the legislation. But the spokesman did not address the accusation of double counting.

"Mischaracterizing what the CBO has said about Medicare savings is just the latest desperate stunt in a last-ditch defense of the status quo," Reid spokesman Jim Manley said.

"The CBO has been very clear: the Senate health reform bill reduces the national deficit by $132 billion dollars in the first decade, and by as much as $1.3 trillion in the decade after," he added.

Once the Senate measure is passed, it has to be merged with legislation passed by the House before a final bill could go to President Obama.

House liberals insisted Wednesday that certain provisions be included in the final bill, including a government-run insurance plan that was dropped in the Senate legislation as part of the concessions made to moderates to secure 60 votes.

"For Congress to achieve true health care reform we must have a meaningful conference process that integrates both bills into the best possible piece of legislation for the American people," California Reps. Lynn Woolsey and Barbara Lee said in a joint statement.

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